Papers by Keyword: Bismuth Ferrite

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Authors: Chun Lin Fu, Meng Huo, Wei Cai, Xiao Ling Deng
Abstract: BiFeO3 powders were prepared by sol-gel process and calcined at different temperatures. The DTA curve shows an obvious exothermic peak near 480.5°C, the temperature close to BiFeO3 formation temperature, which is agreement with the XRD results (450°C). After calcining at 600°C for 1h, XRD spectra has the emergence of several sharp diffraction peaks, compared with the standard XRD spectrum of the crystal BiFeO3. As the calcining temperature increased, the diffraction peak intensity of the XRD spectra of BiFeO3 gradually increased and the diffraction peaks became sharply, indicating that the grain size gradually became larger. There is a clear endothermic peak near 825.1°C, which is the α phase to β phase transition from the knowledge of the phase diagram and in good agreement with the reported Curie temperature.
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Authors: Ebrahim Mostafavi, Abolghasem Ataie, Mostafa Ahmadzadeh
Abstract: Multiferroic bismuth ferrite, BiFeO3, was synthesized via conventional solid-state reaction method using Bi2O3, Fe2O3 as starting materials. Effects of Bi2O3/Fe2O3 molar ratio and calcination temperature on the phase composition, morphology and magnetic properties of produced powders were systematically studied using XRD, FESEM/EDS and VSM techniques, respectively. The results revealed that BiFeO3 phase with rhombohedral R3c structure with a mean particle size of 40 nm was formed in the sample processed with a Bi2O3/Fe2O3 molar ratio of 1:1 after calcination at 800 °C. Rietveld analysis which was applied to the x-ray diffraction data via MAUD software indicated high purity of 95%wt for the above sample. Deviation from the stoichiometric molar ratio (Bi2O3/Fe2O3: 0.9, 1.1, 1.2) yielded higher content of the intermediate phases of Bi2Fe4O9 and Bi25FeO40. FESEM studies showed that the mean particle size was increased from 40 to 62 nm by increasing calcination temperature from 800 to 850 °C. VSM results for 1:1 molar ratio samples indicated that increasing the calcination temperature from 800 to 850 °C increased saturation magnetization (Ms) from 0.087 to 0.116 emu/g and also coercive field (Hc) from 60 to 100 Oe.
683
Authors: Xiao Lin Liu, Xiao Liang Dou, Huan Ying Xie, Jian Feng Chen
Abstract: Bismuth ferrite (BFO), one of very few multiferroics with simultaneous coexistence of ferroelectric and magnetic ordering, has attracted much attention due to its potential applications for new memory devices. In this work, 30~90 nm BFO powders with single rhombohedral phase were prepared by chemical coprecipitation method and after calcining of 500oC. Photocatalytic properties of the powders and dielectric properties of BFO ceramic were characterized, respectively. Cut-off wavelength of the powders at 590 nm exhibited efficient ultraviolet photocatalytic activity, which has been demonstrated by a photocatalytic result. 0.3g BFO powders can make 10 ppm RhB aqueous solution (100 ml) to decolorize and RhB decomposition rate reached to 95% during 3 hr UV irradiation. BFO ceramic can be obtained by sintering the green disc compacted with BFO powders at 800oC for 1h. Its dielectric constant is t about 250, and its dielectric loss is 0.03 at below 100 oC in the frequency range of 102 ~ 104 Hz and up to 1200 at 200 oC under 1 kHz, respectively. Reduced polarization is found due to higher loss and lower dielectric constant of the ceramic when the measuing frequency is more than 104 Hz. Magnetic hysteresis loop of BFO ceramic also shows weaker magnetic property, which may be attributed to size confinement effect of the nanostructures.
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Authors: Min Fang Zhang, Jing Song Liu
Abstract: The BiFeO3 thin film was prepared by sol-gel process on Pt/Si substrates. The dependences of structural, electrical properties on annealed temperature were studied. X-ray diffraction (XRD) analysis revealed that the pure phase of BiFeO3 thin film was obtained when annealed below 650°C for 60 minutes in air. The film annealed at lower temperature had denser surface morphology, and showed better electrical characteristic.
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Authors: C. Silawongsawat, S. Chandarak, Thanapong Sareein, Athipong Ngamjarurojana, S. Maensiri, Pitak Laoratanakul, Supon Ananta, Rattikorn Yimnirun
Abstract: A perovskite-type phase of Bismuth Ferrite, BiFeO3, powder was synthesized by a solid-state reaction via a rapid vibro-milling technique. The effect of calcination condition on the phase formation, and characterization of BiFeO3 powder was investigated. The formation of the BiFeO3 phase investigated as a function of calcination conditions by TG–DTA and XRD. Morphology, particle size and chemical composition have been determined via a combination of SEM and EDX techniques and vibrating sample magnetometer (VSM) were used to characterize the structures and magnetic properties of prepared samples. The rapid vibro-milling is employed for the first time in this work as a significant time-saving method to obtain single-phase BiFeO3 powders.
237
Authors: S. Chandarak, Thanapong Sareein, Athipong Ngamjarurojana, S. Maensiri, Pitak Laoratanakul, Supon Ananta, Rattikorn Yimnirun
Abstract: A perovskite-type phase of solid solution of BiFeO3-BaTiO3 powders were synthesized by a solid-state reaction via a rapid vibro-milling technique. The effect of calcination condition on the phase formation, and characterization of BiFeO3-BaTiO3 powders were investigated. The formation of the BiFeO3-BaTiO3 phase investigated as a function of calcination conditions by TG–DTA and XRD. Morphology, particle size and chemical composition have been determined via a combination of SEM and EDX techniques and vibrating sample magnetometer (VSM) was used to characterize the structures and magnetic properties of prepared samples. The rapid vibro-milling is employed for the first time in this work as a significant time-saving method to obtain single-phase BiFeO3-BaTiO3 powders.
241
Authors: V.G. Kostishyn, Nikolay N. Krupa, Larissa V. Panina, Vitaliy V. Nevdacha, D.N. Chitanov, V.M. Truhan, N.A. Yudanov
Abstract: Multiferroic films of BiFeO3, (BiLa)FeO3 and (BiNd)FeO3 with various concentration of ions of Bi, La and Nd in dodecahedral sublattice utilising were fabricated on monocrystalline substrates of (001) SrTiO3, (100) MgO and (100) Al2O3 by a number of technological methods: rf sputtering, vacuum laser ablation and metal-organic chemical vapor deposition (MOCVD). The film thickness varied in the range of 30-300 nm. The magnetic and magnetoelectric properties of the obtained films were investigated. The saturation magnetization of BiFeO3 was about 9 emu/cm3 which is typical of strained films of this composition. Doping BiFeO3 films by rear earth ions La (Nd) increases both the magnetisation saturation and Neel temperature, as well as magnetoelectric effects, which is explained by increase in magnetic crystal anisotropy and suppression of spatially modulated magnetic structure. It was demonstrated that the corona discharge treatment resulted in a substantial growth of the magnetisation saturation up to 35% whereas the changes in the Neel temperature were not noticible. This is explained by the induced electret state and giant magnetoelectric effect.
388
Authors: Xiao Ling Deng, Wei Cai, Chun Lin Fu, Yu Qin Zhang, Rong Li Gao, Gang Chen, Jia Mu Huang
Abstract: Pure BiFeO3 ceramics and BiMnxFe1-xO3 (x=0.1, 0.15, 0.2, and 0.25) ceramics were prepared by sol-gel method. A structural phase transition from rhombohedral R3c to triangle R3m occurred in Mn-doped BFO ceramics. Mn-doped BFO ceramics exhibited better crystallinity, larger dielectric constant as well as smaller dielectric loss. Besides, a small nonlinearity of magnetization-field curves M(H) was observed, the remanent magnetization increased with the increase of manganese content, and all the BiMnxFe1-xO3 ceramics showed the typical antiferromagnetic, which could be attributed to the effective decrease in the concentration of oxygen vacancies, and the corresponding structural transition.
188
Authors: Sadia Tasnim Mowri, Quazi Delowar Hossain, M.A. Gafur, Aninda Nafis Ahmed, Muhammad Shahriar Bashar
Abstract: (Bi2O3Fe2O3)0.8(Nb2O5)0.2 was synthesized by solid state reaction method. (Bi2O3Fe2O3)0.8(Nb2O5)0.2 was made for the investigation of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Dielectric property. XRD pattern reveals that three phases were obtained with Bismuth Iron Niobium Oxide. SEM elicits that grain size increases with the enhancement of sintering temperature. Dielectric property decreases with the augmentation of frequency.
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Authors: Ying Bang Yao, Bei Zhang, Long Chen, Yang Yang
Abstract: Nanoparticles of bismuth ferrite (BiFeO3) were fabricated by high-pressure pulsed laser deposition method (PLD) on Pt-coated Si substrates. Effects of the ambient oxygen pressure during deposition (from 1 Torr to 15 Torr) were studied with respect to the microstructures and magnetic properties of the samples. It was found that as the pressure is higher than 5 Torr isolated nanoparticles are formed and the size of these nanoparticles decreases with the deposition pressure. All the nanoparticles exhibit ferromagnetic behavior and the magnetic coercive filed decreases with the particle size.
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